By applying continuous optical scanning to polyacrylamide gel electrophoresis (PAGE), we have been able to study molecular properties and resolution parameters associated with protein concentration profiles which are taken while a protein is subjected to PAGE. The apparent diffusion coefficients, derived from band dispersion (zone width) of a concentration profile, were estimated under a set of chosen conditions for a relatively homogeneous native protein, beta-lactoglobulin B, and also for its reduced subunit, and the SDS-derivative of that subunit. Further, an application of the apparatus to the separation and the identification of a oligocomponent system, such as alloantigens from ragweed pollen extract are currently being undertaken in this laboratory.